I don't know that separates will necessarily be that much better. Unless you are absolutely turning the volume way up in a large room I would think the advantages of seperates would be slight at best.
As good as the VT-12's are reported to be (I have not heard them yet). I don't really think they are designed for the kind of situations where seperates would help out the most - tons of power to all speakers at once.
There might be other places to spend money that would help you out better for less money - like optimal placement of the speakers themselves and/or some accoustic foam in the right places.